Search results for "RADIATION"
showing 10 items of 5298 documents
Shear banding mechanism of plastic deformation in LiF irradiated with swift heavy ions
2012
The effect of ion irradiation on the behavior of plastic deformation at micro- and nanoindentation on (001) face of LiF has been investigated. The irradiation was performed using heavy ions (U, Au, Ti and S) with energy in the range from 3 MeV to 2 GeV at fluences up to 5x1013 ions/cm2. In non-irradiated LiF, the indentation produces dislocation gliding on the {110} planes along the and directions. At high fluence irradiation, the resource of the dislocation slip along the preferable directions becomes exhausted due to immobilization of dislocations by radiation defects and their aggregates. The present study demonstrates the change of the mechanism of plastic deformation from homogenous di…
Stable and transient color centers in Gd3Ga5O12 crystals
2004
The work is devoted to investigation of stable color centers (CC) that are created in Gd3Ga5O12 (GGG) crystals under irradiation with γ-quanta (E = 1.25 MeV, D = 105 Gy ) as well as transient CC created in the crystals under irradiation with pulsed electron beam (E = 0.25 MeV, pulse duration 10 ns, fluence 1012 cm-2, time interval of registration 0-500 ns). On the basis of the performed study of optical absorption spectra of the as-grown and irradiated crystals it was established the correlation between a defect subsystem of as-grown crystals and a type of CC induced by radiation in the crystals. The role of Ca2+ dopant ions in the processes of CC formation is examined. Models of the stable…
Energy transfer from colour centres to the dopant in alkali halides
1997
Abstract Energy transfer from F centres to the dopant ions in photostimulated processes is examined. It was found that in alkali halide systems the radiation defects are disposed in near vicinity of the dopants. Recombination of defects also takes place to a limited extent near the dopant with a fast and high-yield energy transfer to the latter. Role of unrelaxed H centres in the formation of donor-acceptor pairs is discussed. Some special exciton energy transfer mechanisms are analysed as well.
Direct Methane Oxidation on La1-xSrxCr1-yFeyO3-δ perovskite-type oxides as Potential Anode for Intermediate Temperature Solid Oxide Fuel Cells
2016
Abstract La1−xSrxCr1−yFeyO3−δ (x = 0, 0.1, 0.15, 0.2; y = 0, 0.3, 0.5) perovskite-type oxide powders were synthesized by solution combustion synthesis and characterized by X-ray diffraction, X-ray photoelectron spectroscopy and H2-temperature programmed reduction. Selected compositions were studied by CH4-temperature programmed reduction in the absence and in the presence of H2S. Temperature programmed oxidation and structural characterizations were performed in order to discriminate the nature of residual deposits on the catalyst surface. The study about reduction in different methane-based mixture revealed that total and partial methane oxidation occurred in the range ∼450–1000 °C indepen…
Multispectral Photophletysmography for Evaluation of Cutaneous Flowmotions
2021
Human skin may reflect health conditions. Important and possibly diagnostically potent components of microcirculation are slow flow oscillations-flowmotions, however there is a lack of studies in this field. The present pilot study was devoted to evaluation of multispectral imaging photoplethysmography in determination of different components of flowmotions. Eight subjects were enrolled for the study. During resting conditions video was captured from dorsal aspect of hand at seven different wavelength and flowmotion analysis performed. Results indicate that at the resting conditions neurogenic component along with endothelial are dominant regardless of wavelength, while myogenic has the low…
209 New Fricke gel with high sensitivity and low diffusion for 3D-MRI dosimetry
2018
Purpose Fricke gel (FG) dosimeters are good candidates for 3D dose assessment in biological materials. Their effective atomic number and density are similar to those of soft tissue. In view of their chemical and morphological characteristics, FG serve as dosimeters and as phantoms at the same time. FG dosimeters are obtained by incorporating an acidic aqueous solution of ferrous ions Fe2+ into a gel matrix. In order to address the limitations of gels based on natural matrices, we have studied FG produced with a matrix of poly-vinyl alcohol (PVA) cross-linked with glutaraldehyde (GTA). Materials and methods The proposed gel contains 10% w/v of PVA and GTA of 1%w/v. A common formulation agaro…
Determination of New Radical Species in Ammonium Tartrate Dosimeters by CW- and Pulsed-EPR Techniques
2015
Samples of ammonium tartrate irradiated with doses of about 0.1–1 kGy by different beams of ionizing radiation (60Co–γ, 19 MeV protons and 62 MeV per nucleon carbon ions) were studied by continuous-wave electron paramagnetic resonance (cw-EPR) and by pulse-EPR techniques. Careful analysis of the cw-EPR and of the echo-detected EPR spectra allowed the identification of a second radical in the system besides the already known radical formed at high temperature by an hydrogen elimination at C(2) position [M. Brustolon et al., Res. Chem. Int 4:359, 1996]. The spectrum of the radical is compatible with that of a radical obtained by hydroxyl elimination.
Technique for routine output verification of Leipzig applicators with a well chamber
2005
The H-type Leipzig applicators are accessories of the microSelectron-HDR system (Nucletron, Veenendaal, The Netherlands) for treatment of superficial malignancies. Recently, the dose rate distributions in liquid water for the whole set of applicators using both source models available for the microSelectron-HDR afterloaders have been obtained by means of the experimentally validated Monte Carlo (MC) code GEANT4. Also an output table (cGy/hU) at 3 mm depth on the applicator central axis was provided. The output verification of these applicators by the user, prior to their clinical use, present practical problems: small detectors such as thermoluminescent dosimeters or parallel-plate ionizati…
Non-Monotonic Concentration Dependence of the Electro-Phoretic Mobility of Charged Spheres in Realistic Salt Free Suspensions
2020
Using super-heterodyne Doppler velocimetry with multiple scattering correction, we extend the opti-cally accessible range of concentrations in experiments on colloidal electro-kinetics. We here meas-ured the electro-phoretic mobility and the DC conductivity of aqueous charged sphere suspensions covering about three orders of magnitude in particle concentrations and transmissions as low as 40%. The extended concentration range for the first time allows the demonstration of a non-monotonic con-centration dependence of the mobility for a single particle species. Our observations reconcile previ-ous experimental observations made on other species over restricted concentration ranges. We com-par…